Liquid crystal displays (hereinafter also referred to as LCDs) are elements which display characters and images with use of electro-optical characteristics of liquid crystal molecules, and are widely used for products such as cell phones, laptops, liquid crystal display TVs. LCDs usually have a liquid crystal panel having polarizing plates (a front polarizing plate and a back polarizing plate) sandwiching a liquid crystal cell. Normally black LCDs, for example, can provide black display when no voltage is applied. In recent years, higher-resolution LCDs have been produced for various applications. Accordingly, there is a demand for liquid crystal panels showing a higher contrast ratio that leads to sharper display of characters and images.
Examples of the conventional method of improving the front contrast ratio of a liquid crystal panel include a method of reducing the scatter component inside the liquid crystal cell and a method of decreasing the transmittance of polarizing plates to improve the degree of polarization. Employing the method of reducing the scatter component inside the liquid crystal cell requires non-easy measures such as a design change in the cell structure. In contrast, employing the method of decreasing the transmittance of polarizing plates to improve the degree of polarization requires only a measure of changing production conditions of the polarizing plates. This method is therefore known as a way of improving the front contrast ratio comparatively easily.
As a technique of improving the front contrast ratio, each of Patent Documents 1 to 5, for example, discloses a liquid crystal panel that has a liquid crystal cell, a first polarizing plate arranged on one side of the liquid crystal cell, and a second polarizing plate arranged on the other side of the liquid crystal cell. Here, the second polarizing plate has a higher transmittance than the first polarizing plate.
Meanwhile, with regard to a technique of adjusting the transmittances of a pair of polarizing plates, Patent Document 6 discloses a liquid crystal panel that has a liquid crystal cell, a first polarizing plate arranged on one side of the liquid crystal cell, and a second polarizing plate arranged on the other side of the liquid crystal cell. In this liquid crystal panel, the first polarizing plate has a first polarizer and a first retardation layer arranged on the liquid crystal cell side of the first polarizer; the second polarizing plate has a second polarizer and a second retardation layer arranged on the liquid crystal cell side of the second polarizer; the first retardation layer shows an index ellipsoid with a relation nx>ny≧nz; the second retardation layer shows an index ellipsoid with a relation nx=ny>nz; and a transmittance (T1) of the first polarizing plate is higher than the transmittance (T2) of the second polarizing plate.
Further, liquid crystal displays have been developed which are provided with an optical element providing a polarizing effect except polarizing plates, such as a brightness enhancing film and a wire gird polarizer. More specifically about liquid crystal displays having an optical element such as a wire grid, Patent Document 7, for example, discloses a liquid crystal display provided with a wire grid polarization optical element. This optical element has a structure with a dielectric part and an anisotropically shaped metal part produced by forming a metal membrane on a transparent, flexible substrate, and extending the substrate and the metal membrane at temperatures below the melting point of the metal membrane. Here, the short length of the structure is shorter than the wavelength of light, and the long length of the structure is longer than the wavelength of light.
[Patent Document 1]
    Japanese Kokai Publication No. 2007-298958[Patent Document 2]    Japanese Kokai Publication No. 2008-9388[Patent Document 3]    Japanese Kokai Publication No. 2008-15307[Patent Document 4]    Japanese Kokai Publication No. 2008-33250[Patent Document 5]    Japanese Kokai Publication No. 2008-58980[Patent Document 6]    Japanese Kokai Publication No. 2007-328217[Patent Document 7]    Japanese Kokai Publication No. 2001-74935